for fun, these are the elite siblings I remembered quickly:
kenenisa (older) > tariku
bernard (older) > robert
jorge > eduardo (twins)
jonathan (twin, oldest) > kevin (twin, oldest) > dylan (youngest) > olivia (middle, using iaaf scoring table for gender comparison)
genzebe (youngest) > tirunesh (middle) > ejegayehu (oldest)
saif > abraham (older)
mo > all brothers
ryan (older) > chad
ryan (oldest) > nate > others (I don't think the others ran)
zane > jake (twins)
henrik (oldest) > filip (youngest) > jakob (middle)
matt > lauren (older)
lopez (oldest) > alex (youngest) > peter (middle)